Evolution of Protein Molecules

Sulfate radical-based advanced oxidation processes (SR-AOPs) employing heterogeneous catalysts to generate sulfate radical (SO4 −) from peroxymonosulfate (PMS) and persulfate (PS) have been extensively employed for organic contaminant removal in water. This article aims to provide a state–of–the–art review on the recent development in heterogeneous catalysts including single metal, mixed metal, and nonmetal carbon catalysts for organic contaminants removal, with particular focus on PMS activation. The hybrid heterogeneous catalyst/PMS systems integrated with other advanced oxidation technologies is also discussed. Several strategies for the identification of principal reactive radicals in SO4 −–oxidation systems are evaluated, namely (i) use of chemical probe or spin trapping agent coupled with analytical tools, and (ii) competitive kinetic approach using selective radical scavengers. The main challenges and mitigation strategies pertinent to the SR-AOPs are identified, which include (i) possible formation of oxyanions and disinfection byproducts, and (ii) dealing with sulfate produced and residual PMS. Potential future applications and research direction of SR-AOPs are proposed. These include (i) novel reactor design for heterogeneous catalytic system based on batch or continuous flow (e.g. completely mixed or plug flow) reactor configuration with catalyst recovery, and (ii) catalytic ceramic membrane incorporating SR-AOPs.

Generation of sulfate radical through heterogeneous catalysis for organic contaminants removal: Current development, challenges and prospects

Removal of pharmaceuticals and personal care products (PPCPs) from wastewater: A review.

The diversity of bacteria and archaea associating on the surface and interior of maize roots (Zea mays L.) was investigated. A bacterial 16S rDNA primer was designed to amplify bacterial sequences directly from maize roots by PCR to the exclusion of eukaryotic and chloroplast DNA. The mitochondrial sequence from maize was easily separated from the PCR-amplified bacterial sequences by size fractionation. The culturable component of the bacterial community was also assessed, reflecting a community composition different from that of the clone library. The phylogenetic overlap between organisms obtained by cultivation and those identified by direct PCR amplification of 16S rDNA was 48%. Only 4 bacterial divisions were found in the culture collection, which represented 27 phylotypes, whereas 6 divisions were identified in the clonal analysis, comprising 74 phylotypes, including a member of the OP10 candidate division originally described as a novel division level lineage in a Yellowstone hot spring. The predominant group in the culture collection was the actinobacteria and within the clone library, the a-proteobacteria predominated. The population of maize-associated proteobacteria resembled the proteobacterial population of a typical soil community within which resided a subset of specific plant-associated bacteria, such as Rhizobium- and Herbaspirillum-related phylotypes. The representation of phylotypes within other divisions (OP10 and Acidobacterium) suggests that maize roots support a distinct bacterial community. The diversity within the archaeal domain was low. Of the 50 clones screened, 6 unique sequence types were identified, and 5 of these were highly related to each other (sharing 98% sequence identity). The archaeal sequences clustered with good bootstrap support near Marine group I (crenarchaea) and with Marine group II (euryarchaea) uncultured archaea. The results suggest that maize supports a diverse root-associated microbial community composed of species that for the first time have been described as inhabitants of a plant-root environment.

The Diversity of Archaea and Bacteria in Association with the Roots of Zea mays L.

The microbial consortium involved in anaerobic digestion has not yet been precisely characterized and this process remains a ‘black box’ with limited efficiency. In this study, seven anaerobic sludge digesters were selected based on technology, type of sludge, process and water quality. The prokaryotic community of these digesters was examined by constructing and analysing a total of 9890 16S rRNA gene clones. Libraries were constructed using primers specific for the Bacteria and Archaea domains for each digester, respectively. After phylogenetic affiliation, the libraries were compared using statistical tools to determine the similarities or differences among the seven digesters. Results show that the prokaryotic community of an anaerobic digester is composed of phylotypes commonly found in all anaerobic digesters sampled and also of specific phylotypes. The Archaea community is represented by an equilibrium among a restricted number of operational taxonomic units (OTUs). These OTUs are affiliated with Methanosarcinales, Methanomicrobiales and Arc I phylogenetic groups. Statistical analysis revealed that the Bacteria community can be described as a three component model: one-third making up a core group of phylotypes common to most of the digesters, one-third are phylotypes shared among a few digesters and another one-third are specific phylotypes. The core group is composed of only six OTUs affiliated with Chloroflexi, Betaproteobacteria, Bacteroidetes and Synergistetes. Its role in anaerobic degradation appears critical to investigate. This comparison of anaerobic digester populations is a first step towards a future understanding of the relationship among biodiversity, operating conditions and digester efficiency.

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Towards the definition of a core of microorganisms involved in anaerobic digestion of sludge

Bioaugmentation as a tool to enhance the removal of refractory compound in coke plant wastewater

A culture-independent phylogenetic survey for an anaerobic trichlorobenzene-transforming microbial community was carried out. Small-subunit rRNA genes were PCR amplified from community DNA by using primers specific for Bacteria or Euryarchaeota and were subsequently cloned. Application of a new hybridization-based screening approach revealed 51 bacterial clone families, one of which was closely related to dechlorinating Dehalobacter species. Several clone sequences clustered to rDNA sequences obtained from a molecular study of an anaerobic aquifer contaminated with hydrocarbons and chlorinated solvents (Dojka et al., Appl. Env. Microbiol. 64:3869-3877, 1998).

Werner Hegemann

Papers

Bioaugmentation as a tool to enhance the removal of refractory compound in coke plant wastewater

Phylogenetic analysis of an anaerobic, trichlorobenzene-transforming microbial consortium

Microbial degradation of quinoline by immobilized cells of Burkholderia pickettii

Anaerobic treatment of tannery wastewater with simultaneous sulphide elimination

Anaerobic toxicity and biodegradation of formaldehyde in batch cultures